106 PROTOZOAN PARASITISM 



work, in which the positive occurrence of E. gingivaUs 

 in forty-two cases of pyorrhoea and the absence of it 

 in normal mouths was reported. This report of 

 Smith and Barrett states a belief in the pathogenicity 

 of the amoeba on account of its constant association 

 with the disease, its absence from normal gums, its 

 tissue cell inclusions, and the elimination of the 

 amoeba and improvement of the disease by treatment 

 with emetine. 



Chiavaro (1914) published a report immediately 

 following this, in which he ascribed no etiological role 

 to the amoeba which he observed in twenty-two cases 

 of pyorrhoea and a few out of a number of cases of 

 dental caries. 



Also in 1914, Bass and Johns recorded the presence 

 of E. gingivaUs in pyorrhoea in eighty-two cases. 

 These investigators (1915A and 191oB) later pub- 

 lished a report of three hundred cases of pyorrhoea 

 harboring the amoeba and also a book presenting their 

 observations and ideas on the subject. They were 

 convinced of the etiological relation of the amoeba 

 to pyorrhoea alveolaris and of the relief to the infec- 

 tion and the progress of the disease attending treat- 

 ment with emetine. 



Further investigation by Smith, Middleton and 

 Barrett (1914), by Smith and Barrett (1915) and by 

 Evans and Middleton (1915) enlarged the field to in- 

 clude consideration of the presence of E. gingivaUs 

 in the tonsils, and the suggested relationship of 

 systemic complications such as arthritis and anaemia. 



